理想气体任意准静态过程的温度变化规律

本文以N_v=P P′V作为温度升降的判据,通过对所有微过程的温度增减分析,总结了理想气体在任意准静态过程中的温度变化规律。     

对《SPWM变频调速应用技术》中关于恒压供水主体方案讨论的商榷

自动化新技术丛书《SPWM变频调速应用技术》(张延滨编著)是一本非常好的书,但书中关于恒压供水主体方案的讨论一节的观点有待商榷,本文对恒压供水主体方案的确定举例进行了分析,并提出恒压供水主体方案确定应考虑系统的运行方式,经综合比较分析最终确定合理的方案。     

夸克和轻子质量经验公式的理论分析

通过量子场论,W-S标准模型SU(5)模型及混沌理论,分析了三代轻子、夸克质量的经验公式,并揭示了me、mμ、mτ及mq之间的内在联系.     

带机会约束的动态投资决策模型研究

本文在BlackScholes型市场中,建立了具有投资机会约束的CaR动态投资决策模型: ,其中x是初始财富,π(t)=(π₁(t),…,π_d(t))′∈R^d为可行的证券组合过程,X^π(T)为计划期末的财富水平,CaR(x,π,T)为投资期末的在险资本,R是投资者事先给定的某正的财富水平,0<β<1通过对该模型的讨论,得到了最优常数再调整策略的显式表达式,其金融学含义包括:对于机会约束下的动态投资组合,在风险中性市场中,最优的常数再调整投资策略是纯债券投资策略,最优的在险资本值为零;在风险非中性市场中,最优的常数再调整投资策略蕴涵了共同基金定理的成立。     

Additive Risk Model Using Piecewise Constant Hazard Function

We study a weighted least squares estimator for Aalen's additive risk model with right-censored survival data which allows for a very flexible handling of covariates. We divide the follow-up period into intervals and assume a constant hazard rate in each interval. The model is motivated as a piecewise approximation of a hazard function composed of three parts: arbitrary nonparametric functions for some covariate effects, smoothly varying functions for others, and known (or constant) functions for yet others. The proposed estimator is an extension of the grouped data version of the Huffer and McKeague (1991 Huffer , F. W. , McKeague , I. W. ( 1991 ). Weighted least squares estimation for Aalen's additive risk model . Journal of the American Statistical Association 86 : 114 – 129 .[Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) estimator. For our model, since the number of parameters is finite (although large), conventional approaches (such as maximum likelihood) are easy to formulate and implement. The approach is illustrated by simulations, and is compared to the previous studies. The method is also applied to the Framingham study data.     

定压外边界的双孔介质复合储层压力分布求解分析

针对外边界定压的双孔介质复合储层模型,研究了两种内边界条件下的变流率问题的无因次内、外区储层压力分布的Laplace空间解;此研究,无疑是对试井分析理论的一种完善,对相应的试井分析软件的研制具有应用价值。     

An Approximation Scheme for Bin Packing with Conflicts

In this paper we consider the following bin packing problem with conflicts. Given a set of items V = {1,..., n} with sizes s₁,..., s (0,1) and a conflict graph G = (V, E), we consider the problem to find a packing for the items into bins of size one such that adjacent items (j, j) E are assigned to different bins. The goal is to find an assignment with a minimum number of bins. This problem is a natural generalization of the classical bin packing problem.We propose an asymptotic approximation scheme for the bin packing problem with conflicts restricted to d-inductive graphs with constant d. This graph class contains trees, grid graphs, planar graphs and graphs with constant treewidth. The algorithm finds an assignment for the items such that the generated number of bins is within a factor of (1 + ) of optimal provided that the optimum number is sufficiently large. The running time of the algorithm is polynomial both in n and in .     

四元交互体系Li，K／Cl，SO_4—H_2O50℃，75℃相关系研究

用恒温方法研究了四元交互体系Ｌｉ，Ｋ／Ｃｌ，ＳＯ４—Ｈ２Ｏ５０℃，７５℃的平衡溶解度．该系统（５０℃，７５℃）的相图是由六条单变量线组成，且有五个结晶区，三个单变点．其中的一点是一致性单变点，其余的点是非一致性单变点．采用混合电解质溶液理论Ｐｉｔｚｅｒ模型，用所测得的该系统的溶解度数据可获得Ｐｉｔｚｅｒ参数．测定了该体系（２５℃）的溶解度、平衡溶液的密度、折光率；平衡固相的溶度积、蒸汽压．计算结果与实测结果一致．     

宇宙在永恒地前进地循环着

本文从广义相对论理论出发,论述了宇宙演化的基本规律;指出了有限宇宙循环的前进性和无限宇宙循环的同一性。     

The inverse gaussian distribution: Some properties and characterizations

This article presents some structural properties of the inverse Gaussian distribution, together with several new characterizations based on constancy of regression of suitable functions on the sum of n independent identically distributed random variables. A decomposition of the statistic λσ (X^?1_i?X^?1) into n - 1 independent chi-squared random variables, each with one degree of freedom, is given when n is of the form 2^r.